cyanogenic

Cyanogenic is an adjective used to describe substances that can release hydrogen cyanide (HCN) under certain conditions. The term is often applied to cyanogenic glycosides, plant-derived compounds that are stored in an inactive form and become toxic when enzymatically hydrolyzed.

In plants, cyanogenic glycosides serve as chemical defenses against herbivores. When plant tissue is damaged, specific β-glucosidase enzymes cleave the sugar part of the glycoside, producing unstable intermediates that release HCN, especially under acidic conditions in the gut of herbivores or during processing. Notable examples include amygdalin in bitter almonds, prunasin in various Prunus species, linamarin in cassava and flaxseed, and dhurrin in sorghum. The distribution of cyanogenic compounds spans several plant families, with both seeds and leaves potentially containing toxins.

Toxicology and mechanism of action: Hydrogen cyanide is a potent inhibitor of cytochrome c oxidase in the mitochondrial electron transport chain, impairing cellular respiration. Acute exposure can cause headache, dizziness, confusion, rapid breathing, cardiovascular collapse, or death, depending on dose and duration. Chronic exposure to dietary cyanogens, particularly from inadequately processed cassava, has been linked to neurological disorders such as konzo in some regions.

Safety and processing: Many cyanogenic foods require proper preparation to reduce toxin levels. Cassava roots and leaves are typically peeled, grated, fermented, sun-dried, or cooked to lower cyanide content. Varieties with reduced cyanogenic potential are cultivated in some areas. Understanding cyanogenic compounds helps balance their ecological role in plants with the need to minimize human and animal health risks.